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no check engine light and will not rev past 2000 rpm

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Hello everyone, I just bought a 97 ES300 with 89k miles and previous owner told me that the car wont rev past 2k rpm and had it checked out at few shops with no clear answer to what's causing her problem's'. As an technician my self, I did the usual check up and found no problems so far.  things I've checked and replaced so far are, checked EGR, TPS, AIC, MAF, coil output, timing belt, spark plugs, vacuum lines, and scanned for codes. I've replaced upper plenum gasket, valve cover gaskets, TPS, MAF and IAC valve "second hand/used" and still same problem. Also noticed that this problem only occurs once the engine warms up: for example, during cold start, she'll rev freely as much as I want her to but as the engine warms up, the rpm will drop like hitting rev limiter. I've timed her as follow. cold start, redline close to 6800 rpm, 2 minutes later 5k rpm, 5 min 3500rpm, 10min+ 2k rpm. I am stumped at this problem, especially with no CEL on and was wondering if someone else had this issue's' with their ES300 or other models. Any help will be greatly appreciated and thank you for taking your time to read this. Cheers. 

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The check engine light is mainly for when something is amiss with pollution output and those things can send the car into limp mode. 

Things like clogged tranny filter or PCV can cause the car to go into limp mode. Valves out of adjustment can also cause limp mode without a code. I read somewhere that the throttle body has issues and can cause limp mode. 

If you know how to use a vacuum tester that would likely show what is out of spec mechanically but not cause a CEL code. 

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 no CEL = no limp mode.  what I did find out so far is LTFT from bake 2 was 13.3% while bank 1 was within spec. discovered clogged injector and bad fuel damper. replaced all bank 2 injectors and damper along with new Denso fuel pump. STFT and LTFT is below 10% now like it suppose to be but same engine problem. runs beautifully when engine is cool but once the engine temp rise " ECT 160F+ and AIT above 80F " fuel on closed loop, engine will not rev past 3k rpm like hitting a rev limiter. engine vacuum hold steady at 14.1 during idle. 

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  • 2 weeks later...

problem solved after 3 weeks of on and off diagnostic. it was the crank sensor that failed and this was very difficult problem to diagnose because the crank sensor did work " to a degree ".  previous owner sold me this car for 1200 with only 89k miles because 4 or 5 shops that she took this ES300 to couldn't figure out the problem including 2 Lexus dealerships and 1 of them even suggested a new/rebuild motor because they thought somehow, the compression loss after engine warm up while running.  I've been turning wrench as a master tech since 2001 and never encountered this problem before. not sure as to unique problem, only for Toyota or not but it was hard problem for sure.  if you want details of how and what way the sensor failed or any questions about leading up to my findings, let me know. 

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